aura vs hidden meaning

aura

noun
  • Telltale sensation experienced by some people with epilepsy before a seizure. 

  • An invisible force surrounding a living creature. 

  • Perceptual disturbance experienced by some migraine sufferers before a migraine headache. 

  • Distinctive atmosphere or quality associated with something. 

hidden meaning

How often have the words aura and hidden meaning occurred in a corpus of books? (source: Google Ngram Viewer )